MetService has issued a severe weather outlook for parts of New Zealand in the week ahead.

"Heavy rain and gales are possible for parts of the South Island from late Monday," says a MetService spokesperson.

A front is forecast to move east onto the south of the South Island late on Monday bringing northwest gales to many exposed areas and possibly warning amounts of rain to Fiordland and the ranges of Westland.

There is moderate confidence of rainfall reaching warning amounts about Fiordland from late afternoon on Monday, and the ranges of Westland during the evening.

There is moderate confidence that northwest winds could reach severe gale about exposed parts of Canterbury High Country, inland Otago, Southland, including Stewart Island, and parts of Fiordland during the late afternoon or evening on Monday, while there is low confidence of severe west or northwest gales in exposed parts of the Tararua District and northern Wairarapa at various times.

On Tuesday March 26, a front is expected to move northwards onto the South Island while weakening. Another front is forecast to approach Fiordland late in the day. 

There is moderate confidence of warning amounts of rainfall during Tuesday morning in the ranges of Westland and in Fiordland, and in Fiordland again from Tuesday evening onwards.

There is moderate confidence that northwest winds could reach severe gale about exposed parts of Canterbury High Country during Tuesday morning and at night. There is low confidence of severe northwest gales for inland Otago, Southland, including Stewart Island, and parts of Fiordland during the early morning, then again at night. There is low confidence of severe west or northwest gales in exposed parts of the Tararua District and northern Wairarapa all day.

On Wednesday, March 27, a couple of weakening fronts is expected to cross the country. A third front will be approaching Fiordland late in the day. 

There is low confidence of rainfall reaching warning amounts about northern Fiordland and the ranges of Westland during Wednesday morning.

There is low confidence that northwest winds could reach severe gale in exposed parts of the Canterbury High Country during Wednesday morning. There is low confidence that west or northwest winds could reach severe gale in exposed parts of the Tararua District, Wairarapa and Wellington at various times.

On Thursday March 28, a front will be moving across the country. There is low confidence of warning amounts of rain in Fiordland and the ranges of Westland during the morning. 

There is also low confidence that northwest winds could reach severe gale in exposed parts of the Canterbury High Country during Thursday morning.

People are advised to keep up to date with the latest forecasts.